When the tributes are selected at the start of the film is the selection process rigged? It's implied during the film that the selection process is random, but there are a few indicators that it might not be.

During the start of the film Katniss Everdeen is talking with a boy on the hill, and he says he's entered the contest 42 times. That number seems unusually high to me.

When the announcer woman is selecting names from the large fish bowl. She hand picked them without mixing the cards. She could easily grab pre-selected cards.

During the hunger games the controllers use fire to redirect Katniss back into the action of the game. If they're willing to cheat to get people killed, then why not rig the selection?

Later in the film President Coriolanus Snow talks to Seneca Crane about controlling hope and how they created the games to control sectors, by limiting how much hope they have of winning. He implies that Seneca should try to get Katniss killed, and this makes me think she wasn't intended to enter the games.

Is there anything in the film or book that confirms the selection process is rigged? and if it is rigged, then why?

As @Mathew notes, certainly the second book/movie was rigged, inasmuch as the rules were changed so as to ensure that Katniss’ name would be the only name in the girls’ bowl. The Catching Fire trailer confirms as much.

As for the first book, though, no, there’s nothing in the book or movie to imply that the selections were rigged. Not that this means that they weren’t, but it’s just one of the many details that the book and film leave ambiguous. You could argue that the quasi-rigged nature of the second book’s selection implies that the selection in the first book was likely rigged as well. But I would counter, for what purpose would the authorities have deliberately selected the original choices of Peeta and Prim? Neither one seemed to pose any threat to the state to make them worth eliminating, nor did either one seem to present much opportunity for juicy television. It’s even more of a stretch to assume that Prim was chosen to entice Katniss to volunteer in her place, as volunteers in District 12 are said to be rare; and at that point in the story, it’s unclear that the authorities would have had anything against Katniss either (or known about the potential love angle with Peeta). If the authorities had wanted Katniss in the Games, presumably they would have simply chosen her.